Secretary of State William H. Seward who orchestrated the purchase of Alaska actually wanted to annex the entire pacific coast. The annexation bill of 1866 which never really went anywhere proposed voluntary annexation of British Columbia. A second proposal in 1867 also provided for voluntary annexation of British Columbia. In both cases the U.S. would have paid about 10,000,000 for the territory. There was a pretty significant movement in British Columbia to join the United States. When the United States purchased Alaska Britain feared losing British Columbia and quickly added it to Canada.

U.S. Secretary of State Seward wanted to acquire all of the Pacific coast for the United States. At one point he floated the idea of settling the Alabama Claims for British Columbia but was never able to get a committed response from Britain on whether this was a possibility.

The U.S. never made a serious offer to buy British Columbia. Britain never made an offer to sell it probably because in 1867 they had mostly forgotten it existed.